How to speed up a render time for Mental Ray rendering.

There are so many ways to speed up a render and these are some quick tip for it. Some tips are not only for Mental Ray.

1 - Use a proxy object for a car, tree, people, furniture and etc.. (High poly objects) This helps a lot.

2 - When you send a render, change a view port display to Bounding Box.
3 - Try to avoid using ‘Force 2-Sided’ option under Render Setting > Common > Options

4 - Turn off ‘Rendered Frame Window’ under Render Setup > Common > Render Output. Net render also has a same option.

5 - Lower samples. Try Min – 1 and Max – 4 and if you are not satisfying the quality then use higher samples.

6 - Use BSP2 under Render Setup > Renderer > Rendering Algorithms > Raytrace Acceleration (Especially a scene is big)

7 - Save Final FG and GI maps under Render Setup > Indirect Illumination > Reuse

8 - Use a net render or bucket render.

9 - Make sure your model is close to 0,0,0 point.

10 - Don't use a big image file for a material.

11 - Merge all modifiers.
12 - If objects are far from a camera, make a material simple. No refrection No bump
13 - If you bring models from SketchUp, check materials. Maybe there are 100s of multi sub materials. I usually delete or clean up those materials.
14 - Use 'Draft' setting for Final Gather. Also render out AO map and do some post.
15 - More lights = Slow render. For an interior scene, use Global Illumination and put min interior lights.
16 - No Global Illumination for exterior scenes. Not 100% but most of the time.
16 - Try to avoid using Autodesk Material Library materials. Use A&D materials.
17 - For A&D material, keep Reflection Glossy Samples 8 (I mean don't put too high number) if you can. High number = slow render
Check this link. How to make flat metal.
http://mentalraytips.blogspot.com/2007/11/more-hidden-gems-miaenvblur-gloss.html